1. Field
This application generally relates to the field of wireless communication systems, and more particularly to signals and protocols to enhance data transmission efficiency in such systems.
2. Related Art
The subject matter set forth herein is applicable to wireless communication systems generally. However, it has been developed primarily in the context of cellular telecommunication systems, which facilitate high-speed connectivity and data and voice transport on both point-to-point and point-to-multipoint bases. First-generation (analog) and second-generation (digital) cellular networks were used primarily for communicating voice traffic via mobile cellular telephones, and thus maintained a focus on access methods for the efficient transport of voice information. With the rising popularity of the Internet, a third-generation (3G) wideband multimedia cellular network has been proposed that transports both voice and data at much higher speeds than were previously available using the first and second generation wireless networks.
A Third Generation Partnership Project 2 (3GPP2) has been established by industry groups for the purpose of defining specifications to transition current code-division multiple-access (CDMA) wireless networks to the third generation, which is commonly referred to as CDMA2000. One such specification may be referred to as “CDMA2000 1x Revision D” (which may also be referred to as “CDMA2000 1x Rev D,” “cdma2000 Release D,” “IS-2000-D”, or “IS-2000-Rel. D”). The CDMA2000 1x Rev D specification, available from the 3GPP2, is incorporated by reference herein in its entirety for its teachings on communications protocols used in 3G wireless communications systems.
Many proposals of communication protocols for use in CDMA2000 Release D have been submitted to the 3GPP2, including protocols for both forward link transmissions from a base station (BS) to a mobile station (MS), and for reverse link transmissions from an MS to a BS. Recently, it was decided that incremental redundancy (IR) will be used for Rel. D reverse link, at least for higher data rates. A synchronous 4-channel hybrid ARQ scheme has been suggested using up to 3 unique subpackets (SPID=00, 01, 10) for each packet. The self-decodable SPID=00 contains all systematic bits and will be transmitted first. The subsequent subpackets contain error checking and correction for the first, self-decodable subpacket, but do not provide sufficient information to reconstruct the content of the packet in the absence of some information from SPID=00.
The R-PDCH includes 4 HARQ channels, allowing four time slots for transmission of each packet. Only three of these slots will be occupied by SPIDs 00, 01, and 10. Accordingly, slot time is available for sending an additional subpacket in the event of decoding failure after 3 sub-packet transmissions. There has been discussion of adopting the SPID sequencing of “00-01-10-00,” with retransmission of SPID=00 indexed by 11 because only 2-bits are used for SPID in case that no ACID is used. (An ACID identifies a new HARQ channel, thus indicating the start of a new packet.) Another approach would entail coding the first subpacket as “00” or “11”, toggling in consecutive packets so that the 2-bit SPID field serves both as subpacket indicator and AISN.
Clearly, the present IR protocol does not employ the available subpacket slots to convey data as efficiently as possible to the receiver. A need exists for a method and apparatus that will provide subpackets to the receiver in a manner that better utilizes the available slots, and that matches the provided subpackets to the needs of the receiver. A method and apparatus is set forth below to address this need, and will be seen to include a tool that is applicable to many other signaling functions, particularly in packet data communication systems.